U.S. patent application number 15/120719 was filed with the patent office on 2017-03-02 for eccentric stabilizer for use in a synchronous rotary steerable system.
The applicant listed for this patent is WEATHERFORD/LAMB, INC.. Invention is credited to Roger P. Bartel.
Application Number | 20170058617 15/120719 |
Document ID | / |
Family ID | 52627580 |
Filed Date | 2017-03-02 |
United States Patent
Application |
20170058617 |
Kind Code |
A1 |
Bartel; Roger P. |
March 2, 2017 |
Eccentric Stabilizer for Use in a Synchronous Rotary Steerable
System
Abstract
A method and apparatus for steering a drilling assembly (200)
during drilling operations for oil and gas. The steering assembly
being disposed in a borehole (10) and comprising a drill bit (120)
attached to a drill collar (210) having an eccentric stabilizer
(220) disposed thereupon. The eccentric stabilizer either in an
engaged state whereupon rotating concentrically with the drill
collar, or in a released state whereupon as the drill collar
rotates the eccentric stabilizer is positioned eccentrically
relative to the drill collar creating a lateral deflection in the
borehole that may be used for changing the direction of the
drilling assembly.
Inventors: |
Bartel; Roger P.; (Spring,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WEATHERFORD/LAMB, INC. |
Houston |
TX |
US |
|
|
Family ID: |
52627580 |
Appl. No.: |
15/120719 |
Filed: |
February 23, 2015 |
PCT Filed: |
February 23, 2015 |
PCT NO: |
PCT/US2015/017048 |
371 Date: |
August 22, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61943770 |
Feb 24, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 17/1014 20130101;
E21B 7/062 20130101 |
International
Class: |
E21B 17/10 20060101
E21B017/10; E21B 7/06 20060101 E21B007/06 |
Claims
1. A downhole assembly coupling to a drilling string for drilling a
borehole, the assembly comprising: a drill body rotating with the
drillstring; an engagement mechanism disposed on the drill body and
operable between engaged and disengaged conditions; a drill bit
rotating with the drill body for drilling the borehole; and a
rotatable stabilizer eccentrically disposed on the drill body, the
rotatable stabilizer rotating with the drill body when engaged by
the engagement mechanism in the engaged condition, the rotatable
stabilizer being rotatable eccentrically relative to the drill body
when released by the engagement mechanism in the disengaged
condition, the rotatable stabilizer eccentrically rotated relative
to the drill body and creating a lateral force on the drill body to
change drilling trajectory thereof.
2. The assembly of claim 1, wherein the drill body comprises an
eccentric section on which the at least one rotatable stabilizer is
rotatably disposed, the eccentric section offset from a rotational
axis of the drill body.
3. The assembly of claim 2, wherein the rotatable stabilizer
comprises a sleeve have an eccentric passage rotatably disposed on
the eccentric section.
4. The assembly of claim 2, wherein the at least one rotatable
stabilizer when engaged by the engagement mechanism positions
concentrically relative to the drill body.
5. The assembly of claim 2, wherein the at least one rotatable
stabilizer when disengaged by the engagement mechanism positions
eccentrically relative to the drill body.
6. The assembly of claim 1, wherein the engagement mechanism
comprises one or more of a pin, a clutch, a spring, a piston, a
valve, a ball-release mechanism, a lock, a slot, or a combination
thereof.
7. A downhole assembly coupling to a drilling string for drilling a
borehole, the assembly comprising: a drill body rotating with the
drillstring; a drill bit rotating with the drill body for drilling
the borehole; an inner sleeve eccentrically disposed on the drill
body and rotatable relative thereto; an outer sleeve eccentrically
disposed on the inner sleeve and rotatable relative thereto; and an
actuator disposed on the drill body and operable between first and
second conditions, the actuator engaged with the inner sleeve and
selectively engageable in the first and second conditions with the
outer sleeve, the actuator in the first condition selectively
engaged with the outer sleeve and orienting a combined eccentricity
of the inner and outer sleeves concentrically on the drill collar,
the actuator in the second condition selectively engaged with the
outer sleeve and orienting the combined eccentricity of the inner
and outer sleeves eccentrically on the drill collar.
8. The assembly of claim 7, wherein the actuator comprises an axial
member slideably engaged with the inner sleeve.
9. The assembly of claim 8, wherein the actuator is linearly and
rotationally movable relative to the drill body.
10. The assembly of claim 7, wherein the actuator comprises a first
stop disposed thereon, the first stop engageable with a first
portion of the outer sleeve when the actuator is in the first
condition.
11. The assembly of claim 10, wherein the actuator in the first
condition radially aligns the first stop with the first
portion.
12. The assembly of claim 10, wherein the actuator comprises a
second stop disposed thereon, the second stop engageable with a
second portion of the outer sleeve when the actuator is in the
second condition.
13. The assembly of claim 12, wherein the actuator in the second
condition radially aligns the second stop with the second
portion.
14. The assembly of claim 7, wherein the actuator comprises a
linear actuator component operable to move a portion of the
actuator linearly relative to the drill body.
15. The assembly of claim 14, wherein the actuator comprises a
clutch component operable to couple at least a portion of the
rotation of the drill body to a portion of the actuator.
16. A method of drilling a borehole with a downhole assembly
coupled to a drilling string, the method comprising: rotating a
drill bit about a rotational axis of the downhole assembly;
directing the rotational axis in the borehole by combining a first
eccentricity of a sleeve relative to a second eccentricity of an
eccentric section of the downhole assembly on which the rotatable
sleeve is disposed; drilling a first trajectory by orienting the
combined eccentricity of the sleeve and the eccentric section
concentric to the rotational axis; and drilling a second trajectory
offset from the first trajectory by orienting the combined
eccentricity of the sleeve and the eccentric section eccentric to
the rotational axis.
17. The method of claim 16, wherein drilling the first trajectory
comprises orienting the eccentric section within an eccentric
passage of the sleeve so that the sleeve is concentric to the
rotational axis; and engaging the sleeve so oriented with the
rotation of the drilling assembly.
18. The method of claim 17, wherein drilling the second trajectory
offset from the first trajectory comprises disengaging the sleeve
from the rotation of the drilling assembly; and orienting the
eccentric section within the eccentric passage of the sleeve so
that the sleeve is eccentric to the rotational axis.
19. A method of drilling a borehole with a downhole assembly
coupled to a drilling string, the method comprising: rotating a
drill bit about a rotational axis of the downhole assembly;
directing the rotational axis in the borehole by combining a first
eccentricity of a first rotatable sleeve relative to the downhole
assembly with a second eccentricity of a second rotatable sleeve
relative to the first rotatable sleeve; drilling a first trajectory
by orienting the combined eccentricity of the first and second
sleeves concentric to the rotational axis; and drilling a second
trajectory offset from the first trajectory by orienting the
combined eccentricity of the first and second sleeves eccentric to
the rotational axis.
20. The method of claim 19, wherein drilling the first trajectory
comprises orienting at least one of the first and second sleeves
relative to the other of the first and second sleeves so that the
combined eccentricity is concentric to the rotational axis.
21. The method of claim 19, wherein drilling the second trajectory
offset from the first trajectory comprises orienting at least one
of the first and second sleeves relative to the other of the first
and second sleeves so that the combined eccentricity is eccentric
to the rotational axis.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Prov. Appl.
61/943,770, filed 24 Feb. 2014.
BACKGROUND OF THE DISCLOSURE
[0002] The complex trajectories and multi-target oil wells require
the directed placement of a borehole's path and the ability to
continually to control or "steer" the direction or path of the
borehole during the drilling operation. Preferably, the path can be
rapidly controlled during the drilling operation at any depth and
target as the borehole is advanced by the drilling operation.
[0003] Directional drilling is complicated by the necessity to
operate a drill bit steering device within harsh borehole
conditions. The steering device is typically disposed near the
drill bit, which terminates a lower or "downhole" end of a
drillstring. Many types of devices known in the prior art have been
used to control the direction of a drill bit. Some devices use
stabilizers having ribs or extensions for engaging the wall of a
borehole and controlling the direction of the drill bit as it bores
through the ground. Other devices may use rotational valve systems
for employing fluid to steering pads, may use magnetic switches to
control directional changes, or may use non-rotatable sleeves for
applying lateral force to a borehole to adjust drilling
trajectories. Examples of some devices used to direct the
trajectory of a drill bit can be found in U.S. Pat. Nos. 4,319,649;
6,840,336; and 7,503,408.
[0004] Many of the devices known in the art either require stopping
the drillstring and/or moving the drillstring in one or two
specified positions to create lateral forces within a borehole.
Also, some devices require the use of motors downhole for drilling
in directions relative to specific positioning of the drill bit, or
employ pistons, pads, or other mechanics for creating lateral
forces in the borehole.
[0005] Unfortunately, there are problems associated with many of
the directional drilling techniques mentioned above. Particularly,
having to stop the drillstring during drilling for either
positioning purposes or for using a downhole motor is inefficient.
Besides the apparent inconvenience of having to stop and start the
drill string and/or position the drillstring relative to preset
positions of the non-rotating component, most systems also require
sliding the drillstring, after having stopped, in the new drilling
direction determined by the direction drilled using the downhole
motor.
[0006] Because of the friction induced on the drillstring and tools
downhole, these methods may be inefficient or even damaging to
downhole components. Further, because of the complexity of using
hydraulic valves to employ pistons, or other methods, a simpler
method for achieving a similar goal may be preferred.
[0007] The subject matter of the present disclosure is directed to
overcoming, or at least reducing the effects of, one or more of the
problems set forth above.
SUMMARY OF THE DISCLOSURE
[0008] A method and apparatus for steering a drilling assembly
during drilling operations for oil and gas. The steering assembly
being disposed in a borehole and comprising a drill bit attached to
a drill collar having an eccentric stabilizer disposed there upon.
The eccentric stabilizer either in an engaged state whereupon
rotating concentrically with the drill collar, or in a released
state whereupon as the drill collar rotates the eccentric
stabilizer is positioned eccentrically relative to the drill collar
creating a lateral deflection in the borehole that may be used for
changing the direction of the drilling assembly.
[0009] The foregoing summary is not intended to summarize each
potential embodiment or every aspect of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1A illustrates a drilling system having a drilling
assembly disposed in a borehole according to the present
disclosure.
[0011] FIG. 1B illustrates the drilling assembly in more
detail.
[0012] FIG. 2A illustrates a more detailed view of an eccentric
stabilizer component of the drilling assembly in an engaged
state.
[0013] FIG. 2B illustrates the stabilizer component of the drilling
assembly in a released state.
[0014] FIG. 3A illustrates a perspective view of the disclosed
drilling assembly having an eccentric section offset from a central
rotational axis of the drilling assembly.
[0015] FIG. 3B illustrates a cross-sectional view of the drilling
assembly in FIG. 3A having the eccentric section offset from the
central axis of the drilling assembly.
[0016] FIG. 4A illustrates the drilling assembly disposed in the
borehole and having the stabilizer component disposed and released
near the drill bit.
[0017] FIG. 4B illustrates the drilling assembly disposed in the
borehole and having the stabilizer component disposed and released
a distance away from the drill bit.
[0018] FIG. 5 illustrates another drilling assembly having an
eccentric stabilizer component according to the present
disclosure.
[0019] FIGS. 6A-6C illustrate various views of the drilling
assembly in different states of assembly.
[0020] FIG. 6D illustrates a schematic end view of the downhole
assembly showing the eccentricity of its components.
[0021] FIGS. 7A-7B illustrate a side view and an end view of the
disclosed drilling assembly oriented for concentric drilling.
[0022] FIG. 8 illustrates the disclosed drilling assembly during an
initial stage of activation.
[0023] FIGS. 9A-9B illustrate a side view and an end view of the
disclosed drilling assembly during eccentric activation.
[0024] FIGS. 10A-10B illustrate a side view and an end view of the
disclosed drilling assembly oriented for eccentric drilling.
[0025] FIG. 11 illustrates a side view of the disclosed drilling
assembly during an initial stage of deactivation.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0026] FIG. 1A illustrates a drilling system 20 having a drilling
assembly 200 suspended in a borehole 10 penetrating an earth
formation. At the surface, a derrick structure 22 supports the
downhole assembly 200 on a drillstring 110 and has a crown block at
the top. A traveling block is moveably connected to the crown block
and serves to connect to the drillstring 110, which is raised and
lowered into the borehole 10 by a cable connected to a drawworks
24. The drawworks 24 is used to release or retract cable, allowing
the traveling block to be raised or lowered, which in turn raises
or lowers the drillstring 110. Finally, a rotary table 26 may serve
to control rotation of the drillstring 110.
[0027] The drilling assembly 200 connected to the drillstring 110
is terminated by a drill bit 120. During drilling operations, the
rotary table 26 imparts rotation to the drill bit 120 by rotating
the drillstring 110 and the drilling assembly 200. For its part,
the drill bit 120 of the drilling assembly 200 may be a
polycrystalline diamond compact (PDC) bit, a rotary drilling bit
rotated by a mud motor and shaft, or any other suitable type of
drill bit 120.
[0028] In addition to the drill bit 120, the drilling assembly 200
can have one or more stabilizer components 220 that are used for
both stabilizing the drilling assembly 200 within the borehole 10
during drilling operations and creating a lateral force in the
borehole 10 for directing the drilling assembly 200 in a particular
direction downhole.
[0029] As shown in more detail in FIG. 1B, the drilling assembly
200 disposed on the drillstring 110 has a controller section 204,
an actuator and sensor section 202, a stabilizer component 220, an
eccentric section 210, an engagement mechanism 230, and the drill
bit 120. As its name implies, the controller section 204 can have
control circuitry, memory, battery power, telemetry components, and
the like to control operation of the drilling assembly 200. The
control section 204 can have sensors for determining near-bit
inclination and azimuth for directional drilling. The actuator and
sensor section 202 can house one or more actuators and position
sensors that operate in conjunction with the control section 204 to
control operation of the drilling assembly 200.
[0030] The stabilizer component 220 can have the form of a sleeve
or the like disposed on the eccentric section 210 of the drilling
assembly 200. The eccentric section 210 is offset from the central
rotational axis C of the assembly 200 to that the stabilizer
component 220 is eccentrically located on the assembly 200.
[0031] The engagement mechanism 230 is operated by the actuator and
sensor section 114 to either engage or release the stabilizer
component 220. When engaged by the mechanism 230, for example, the
stabilizer component 220 rotates with the assembly 200 and the
rotation imparted to it. When released by the mechanism 230,
however, the stabilizer component 220 can rotate relative to the
assembly 200. As discussed below, synchronizing the engagement and
release of the eccentric stabilizer component 220 on the drilling
assembly 200 during rotation can be used to direct drilling of the
borehole 10.
[0032] Referring now to FIG. 2A, an embodiment of the stabilizer
component 220 disposed on the drilling assembly 200 is shown in an
engaged state. As noted above, the stabilizer component 220 is a
sleeve disposed on the eccentric section 210. The stabilizer
component 220 may be composed of high-strength steel or any other
material suitable for use as a stabilizer for a downhole tool in a
borehole. The stabilizer component 220 may also have coatings of
even harder material for additional durability. Moreover, the
diameter of the stabilizer component 220 may vary depending on the
application. For example, the stabilizer component 220 can be the
same diameter of the diameter of the drilling assembly 200;
however, the diameter of the stabilizer component 220 may be larger
or smaller than the diameter of the drilling assembly 200.
[0033] As noted above, the stabilizer component 220 is disposed on
the eccentric section 210, which passes through the stabilizer
component 220. The eccentric section 210 may be an extension of the
drilling assembly 200, having been machined with an inner diameter
different than the diameter of the drilling assembly 200, or may be
otherwise designed, or even be removably connectable to the
drilling assembly 200.
[0034] One or more engagement mechanisms 230 may be disposed within
the drilling assembly 200. In one embodiment, the engagement
mechanism 230 serves to release or lock the stabilizer component
220. The engagement mechanism 230 may either release or lock the
stabilizer component 220 at revolution intervals needed to maintain
the desired drill path. The control parameters can be modified by
communication from the surface and/or autonomously by directives
preloaded into the downhole electronics either at the surface using
an engagement control communicating with the engagement mechanism
230 downhole, or by programing a controller downhole.
[0035] The engagement mechanism 230 preferably takes a minimal
amount of effort and uses as minimal electrical energy as possible
to engage and re-engage the stabilizer component 220 with the
drilling assembly 200. Some mechanisms that may be used include
hydraulic systems with pistons and/or valves, a slip clutch
mechanism, or any disposable object that can be used to lock the
stabilizer component 220 to the drilling assembly 200.
[0036] Other mechanisms for locking and releasing the stabilizer
component 220 may be used. For example, the engagement mechanism
230 may use a pin and spring mechanism for engaging the stabilizer
component 220. The pin of the mechanism 230 can extend and retract
relative to the stabilizer component 220 and may engage and
disengaged from one or more slots 226, stops, locks or the like on
the component 220. In another embodiment, the engagement mechanism
230 may be a multi-plate clutch mechanism, a ball/release
mechanism, or any other suitable feature to lock and release the
stabilizer component 220 relative to the drilling assembly 200.
[0037] When the engagement mechanism 230 is engaged (i.e., the
engagement mechanism 230 has been configured to lock the stabilizer
component 220 in an engaged state) the stabilizer component 220
will be disposed on the drilling assembly 200 being symmetrically
aligned with the center of the drilling assembly 200 (i.e., in a
concentric state). In this configuration, the stabilizer component
220 is connected to the drilling assembly 200. When the drilling
assembly 200 is rotated as a result of rotating the connected
drillstring 110, the stabilizer component 220 will likewise rotate.
In this state, the stabilizer component 220 may help stabilize the
downhole assembly 200, but will significantly direct drilling.
[0038] During drilling, the stabilizer component 220 can engage the
borehole (10) using both friction and drag. Friction acting on the
stabilizer component 220 in a neutral position concentric on the
assembly 110 may assist in persuading the stabilizer component 220
to cam out from the eccentric section 210 once the engagement
mechanism 230 has been released.
[0039] This camming action may be achieved by physical force (e.g.,
flow turbulence) upon the stabilizer 220, or by some mechanical,
electrical, and/or magnetic inducement (e.g., using motors, or
other such devices internal or external) to the drilling assembly
200. Moreover, once the stabilizer component 220 begins camming
outward, additional drag may act on the stabilizer component 220
causing the stabilizer component 220 to eventually reach maximum
eccentricity. Further, to increase friction and/or aid in creating
the drag on the stabilizer component 220, the stabilizer component
220 may contain other friction inducing surfaces or mechanisms to
increase the ability of the stabilizer component 220 to engage the
borehole (10) once released.
[0040] FIG. 2B illustrates the stabilizer component 220 disposed on
the drilling assembly 200 in a released state. As shown by the left
rotation arrow (L), the stabilizer component 220 is movably
connected to the drilling assembly 200, and is only held in a
concentric state with the drilling assembly 200 when locked by the
engagement mechanism 230. Thus, as illustrated, when the stabilizer
component 220 is activated (i.e., when the engagement mechanism 230
is in a released state), the stabilizer component 220 will engage
the borehole 10, while the drilling assembly 200 is allowed to
continue rotation in a right rotation direction, as shown by the
right rotation arrow (R). The above illustration assumes the
drillstring 110 is rotating in the (R) direction (clockwise). The
stabilizer will apparently be rotating to the left (L) direction
(counterclockwise), but it is actually remaining relatively
stationary as it is unlocked from the drillstring. As shown in
FIGS. 2A-2B, the external surface 222 of the stabilizer component
220 can include spiraling ribs, contours, or other features.
[0041] As previously described, the external surface 222 serves to
contact the inside of the borehole (10) when the stabilizer
component 220 is in the released state. However, although regular
re-latching of the stabilizer component 220 will minimize errors
with the stabilizer component 220 slipping in the borehole (10),
due to conditions in the borehole (10), additional friction
generating substances or mechanisms may be used to increase the
ability of the stabilizer component 220 to engage the borehole (10)
when released.
[0042] FIGS. 3A and 3B better illustrate the drilling assembly 200
having the eccentric section 210 offset from the central axis C of
the drilling assembly 200. As revealed, the flow passage 205
through the drilling assembly 200 communicates with flow passage
215 through the eccentric section 210 so that drilling fluid can be
communicated from the drillstring 110 to the drill bit 120. Because
the stabilizer component (220) is disposed on the eccentric section
210 with the eccentric section 210 having an offset from the
central axis C of the drilling assembly 200, the stabilizer
component 220 in a released state creates a lateral deflection
within the borehole (10).
[0043] As described above with reference to FIGS. 2A and 2B, the
stabilizer component 220 is movably connected to the drilling
assembly 200 by way of the eccentric section 210. Also, the
eccentric section 210 is offset from the central axis C of the
drilling assembly 200. When the stabilizer component 220 is in a
released state and rotates relative to the eccentric section 210,
the stabilizer component 220 will be in an eccentric position
relative to the drilling assembly 200. As will be discussed further
below, this eccentric state allows the stabilizer component 220 to
be forced between the drilling assembly 200 and the borehole 10,
thus inducing a lateral force on the drilling assembly 200.
[0044] Referring to the positioning of the eccentric section 210
relative to the drilling assembly 200 in FIGS. 3A and 3B, the
eccentric section 210 is not aligned in the center axis C of the
drilling assembly 200. Instead, the eccentric section 210 is offset
from the central axis C by some amount. Again, this offset allows
the stabilizer component 220 to be in an eccentric position with
respect to the drilling assembly 200. Also, the eccentricity of the
stabilizer component 220 when released relative to the drilling
assembly 200 may depend on the amount the eccentric section 210 is
offset from the central axis C of the drilling assembly 200.
Further, as shown in FIGS. 3A and 3B, the engagement mechanism 230
may also be offset from the central axis C of the drilling assembly
200.
[0045] Referring now to FIGS. 4A-4B, two arrangements of the
disclosed stabilizer component 220 are discussed. As described
above, releasing the stabilizer component 220 while rotating the
drilling assembly 200 creates a lateral deflection in the borehole
10, which in turn can be used to direct the trajectory of the
drilling assembly 200. In other words, the displacement of the one
or more stabilizer components 220 from the drill bit 120 may cause
the drilling assembly 200 trajectory to vary.
[0046] FIG. 4A illustrates one example of the drilling assembly 200
disposed in the borehole 10. The assembly 200 has the stabilizer
component 220 disposed and released near the drill bit 120 by a
distance D.sub.1. The stabilizer component 220 may preferably be
released at the low side of the borehole 10 but may be released at
any disposition in the borehole 10 for creating lateral deflection
in any direction of the borehole 10.
[0047] If the stabilizer component 220 is disposed near the drill
bit 120 at a close distance D.sub.1 as shown, and the engagement
mechanism 230 is released as shown, then the friction of the
external surface 222 of the stabilizer component 220 against the
borehole 10 will begin stalling the stabilizer component 220
relative to the position of the rotating drilling assembly 200.
This stalling creates additional friction on the stabilizer
component 220 because of the camming effect discussed above.
[0048] The stabilizer component 220 will be at maximum friction
when it reaches maximum eccentricity (i.e., when the stabilizer
component 220 rotates substantially near 180 degrees from its
original concentric position). While approaching maximum
eccentricity, the stabilizer component 220 is forced in the
transverse direction (T) creating an opposite force or deflection
in the opposite direction (B). In one embodiment, creating a force
in the direction (B) due to the deflection created by the
stabilizer component's eccentricity may preferentially direct the
drill bit 120 of the drilling assembly 200 to drill on that side of
the borehole 10 in that direction.
[0049] Further rotation of the drilling assembly 200 brings the
stabilizer component 220 back into the concentric position where it
may once again be arrested and locked by the engagement mechanism
230, and may continue rotating concentrically with the rest of the
drilling assembly 200.
[0050] FIG. 4B illustrates another example of the drilling assembly
200 disposed in the borehole 10. Here, the assembly 200 has the
stabilizer component 220 disposed and release a greater distance
D.sub.2 away from the drill bit 120. As described above, releasing
the stabilizer component 220 while rotating the drilling assembly
200 creates a lateral deflection in the borehole 10, which in turn
can be used to direct the trajectory of the drilling assembly
200.
[0051] However, by disposing the stabilizer component 220 the
distance D.sub.2 farther away from the drill bit 120, the lateral
deflection created by the eccentricity of the stabilizer component
220 may actually be used to bend the drill collar of the drilling
assembly 200. This bend in the drill collar may cause the drill bit
120 to be forced in a similar direction (T') as the initial force
in direction (T) created by the eccentricity of the stabilizer
component 220. As a result, depending on the displacement D.sub.2
between the stabilizer component 220 and the drill bit 120, the
resulting trajectory of the drilling assembly 200 may be
different.
[0052] Although, as will be appreciated by those in the art, many
different control techniques may be used to steer the drilling
assembly 200 using the stabilizer component 220 and methods
described above, one control technique is discussed below. In this
technique, the engagement mechanism 230 may be activated every
other rotation of the drilling assembly 200 so that the stabilizer
component 220 is recaptured after each rotation to remain
concentric. Recapture of the stabilizer component 220 may be
necessary because, based on a plethora of mechanical and
environmental variables downhole, the stabilizer component 220 may
not necessarily remain synchronous with the rotation of the
drilling assembly 200.
[0053] To obtain desired real-time directional control, the
drilling assembly 200 preferably operates the steering remotely
from the surface of the earth. Furthermore, the steering can be
operated to maintain the desired path and direction while being
deployed at possibly a great depth within the borehole and while
maintaining practical drilling speeds. Finally, the steering can
reliably operate under exceptional heat, pressure, and vibration
conditions that can be encountered during the drilling
operation.
[0054] Another control technique can release the engagement
mechanism 230 when the desired "heading" of the drilling assembly
200 is directed to a calculated target. During the drilling
operation, for example, control circuitry and sensors may monitor
and record the toolface position when the sleeve of the stabilizer
component 220 has reached maximum eccentricity. As an example, the
sensing can be performed using a Hall Effect sensor or using
torsional measurement. Once the stabilizer component 220 is in an
eccentric position and the drillstring 110 is within a certain area
of desired trajectory, locking the engagement mechanism 230 may be
skipped so that the drilling may continue in the direction of the
desired trajectory. Skipping activation of the mechanism 230 can be
done for one revolution, which in reality may be only a partial
revolution due to lag from the first activation. This
re-synchronizes the stabilizer component 220 to the drilling
assembly 200. This process is then repeated multiple times for a
time cycle (e.g., 60 times if drilling at 120 rpm equating to one
minute).
[0055] During the process, the activation toolface of the mechanism
230 is evaluated relative to the recorded position of the
stabilizer component 220 at its peak eccentricity to determine any
"slippage correction." Thus, if the drillstring 110 has slipped off
of the desired trajectory, the stabilizer component 220 may be
reengaged or locked to adjust the heading while the mechanism 230
is activated to compensate for the measured slippage during the
previous time cycle.
[0056] The entire process may be repeated many times, or modified
to obtain the required trajectory. The stabilizer component 220 may
be locked continuously within the borehole 10 if building an angle
or changing direction of the drilling assembly 200 is not
wanted.
[0057] For this embodiment having the eccentric sleeve of the
stabilizer component 220 on the corresponding eccentric section
210, the drill bit 120 has an active "cutting" face that remains
the same. The cutting face is determined by the random position of
the bit 120 when it is put onto the assembly 200 and is the side of
the bit 120 positioned opposite where the eccentric sleeve 220
reaches its maximum eccentricity. During operations, the active
cutting face will take the brunt of the wear.
[0058] Turning now to FIG. 5, another drilling assembly 300 has an
eccentric stabilizer component 340 according to the present
disclosure disposed thereon. In contrast to the previous
embodiment; this drilling assembly 300 can allow the drill bit 120
to experience more distributed wear during operations. Also, the
drill path created with this assembly 300 may follow a more uniform
trajectory with less lobe shapes produced during directional
changes.
[0059] As before, this drilling assembly 300 includes a drill body
or collar 310 with a drill bit 320 on its distal end. The drill
collar 310 is coupled to an actuator assembly 330, which has a
linear actuator 332, a torque clutch 334, and position sensors 336.
The position sensors 336 in the assembly 330 determine the position
of an actuator 350 so it can be coordinated to the toolface of the
drilling assembly 300 and the eccentric offset that can be achieved
with the stabilizer component 340.
[0060] The actuator assembly 330 is coupled to a control assembly
338 that houses control circuitry 339a and sensors 339b, such as
near-bit inclination and azimuth sensors. The entire drilling
assembly 300 extends from the drillstring 110, which imparts
rotation to the assembly 300.
[0061] The eccentric stabilizer component 340 includes the actuator
350 disposed on the drill collar 310. As previously noted, the
actuator 350 is operatively coupled to the actuator assembly 330,
which can move the actuator 350 axially with the linear actuator
332 and can turn or torque the actuator 350 about the axis of the
drill collar 310 with the clutch 334.
[0062] The stabilizer component 340 includes an inner eccentric
sleeve 360 disposed on the drill collar 310, an outer eccentric
sleeve 370 disposed on the inner sleeve 360, and a stabilizer body
380 disposed on the outer sleeve 370. As will be described in more
detail below, the actuator 350 is engaged with the inner sleeve 360
and is selectively engageable in first and second conditions with
the outer sleeve 370.
[0063] During one form of operation, for example, the actuator 350
moved to the first condition can selectively engage with the outer
sleeve 370 and can orient the combined eccentricity E of the inner
and outer sleeves 360, 370 concentrically on the drill collar 310.
In this way, the stabilizer component 340 is concentric to the
central rotational axis C of the drill collar 310. During another
form of operation, however, the actuator 350 moved to the second
condition can selectively engage with the outer sleeve 370 and can
orient the combined eccentricity E of the inner and outer sleeves
360, 370 eccentrically on the drill collar 310. Controlling these
states can achieve directional drilling.
[0064] FIGS. 6A-6C show the stabilizer component 340 in more detail
in the partial disassembled views. As best shown in FIG. 6C, the
eccentric stabilizer component 340 includes the inner eccentric
sleeve 360 disposed on the drill collar 310, which passes through
an eccentric passage 361 of the inner sleeve 360. The actuator 350
includes an axial member or slide bar 352 disposed in a
longitudinal slot 362 of the inner sleeve 360 so that the actuator
350 and the inner sleeve 360 can rotate together depending on how
the actuator assembly 330 with its clutch (334) operates the
actuator 350.
[0065] In some situations during operation, the clutch (334) of the
assembly 330 allows the actuator 350 to be driven by the rotation
of the drill collar 310 with an amount of torque. In other
situations during operation, the clutch (334) of the assembly 330
is operated so that there is less torque on the actuator 350. The
assembly 330 can therefore use the clutch (334) to selectively
control the extent that the actuator 350 is driven by the drill
collar 310. The clutch (334) as disclosed herein may use static
friction element(s) that will encourage the camming action of the
external sleeve 370.
[0066] As disclosed herein, the actuator's slide bar 352 is
travelling with the eccentric sleeves 360, 370, and the slide bar
352 can be activated in any relationship to the drill collar 310.
Once the slide bar 352 is actuated, camming out the outer sleeve
370 can use a stalling force on the inner sleeve 360 relative to
the drill collar 310 and can also use a stalling force on the outer
sleeve 370 relative to the borehole to cause the sleeves 360, 370
to move differentially to each other. The outer sleeve 370 may have
a spring-loaded wear pad to provide additional friction, even in an
over-gauged borehole.
[0067] The inner sleeve 360 can be magnetically coupled to the
drill collar 310 to produce constant drag, while still allowing the
two pieces to constantly rotate. For example, the magnetic drag can
be produced in the ring portion of the actuator 350, which is
coupled with the inner sleeve 360. When the actuator 350 is slid by
the linear actuator (332), magnetic elements between the ring of
the actuator 350 and the drill collar 310 can overlap and create
the desired drag between the actuator 350 (coupled to the inner
sleeve 360) and the drill collar 310.
[0068] Alternatively, there also may be some other type of
clutching mechanism in that same area. Overall, the actuator 350
may only need to be actuated linearly (and possibly use a spring
return) for the required clutching to occur. All of the other
needed forces can be generated by that one action. As will be
appreciated, too much differential loading between the outer sleeve
370 and the inner sleeve 360 can make it more difficult for the
actuator 350 to operate.
[0069] As best shown in FIG. 6B, the eccentric stabilizer component
340 further includes the outer eccentric sleeve 370 disposed on the
inner sleeve 360, which passes through an eccentric passage 371 of
the outer sleeve 370. The outer sleeve 370 does not include a
longitudinal slot. However, a concentric stop 376 on the outer
sleeve 370 is capable of engaging a distal stop 356 on the slide
bar 352 of the actuator 350. Additionally, the outer sleeve 370
includes an eccentric stop 374 capable of engaging a proximal stop
354 on the actuator 350.
[0070] Depending on the axial and radial position of the slide bar
352 described below, its stops 354, 356 can selectively engage the
outer sleeve's stops 374, 376. In general, the stops 374, 376 on
the sleeve 370 can include tabs or the like extending from opposite
ends of the sleeve 370. The slide bar's stops 354, 356 can be tabs
extending upward from the surface of the bar 352. Other features
for the stops 354, 356, 374, and 376 can be used.
[0071] Finally, as best shown in FIG. 6A, a stabilizer body 380 is
disposed external to the outer sleeve 370. The stabilizer component
340 is intended to be non-rotating in the borehole so the
stabilizer body 380 can include conventional features for
non-rotation as found in non-rotating rotary steerable systems,
such as disclosed in US Pat. Pub. 2014/0262507, which is
incorporated herein by reference.
[0072] It will be appreciated that the views of the stabilizer
component 340 do not show many of the components required for the
stabilizer component 340 to operated downhole during drilling
operations. In other words, protective bodies, seals, bearings,
etc. are not depicted for simplicity. With the benefit of the
present disclosure, however, one skill in the art will recognize
the use and necessity of these and other such features.
[0073] The drill collar 310, the inner sleeve 360, the outer sleeve
370, and the stabilizer body 380 can be oriented concentrically and
eccentrically depending on operation of the actuator 350 by the
actuator assembly 330, as described in more detail below. The
concentric arrangement of these components is schematically
illustrated in FIG. 6D. The inner sleeve 360 is oriented in the
inner passage 371 of the outer sleeve 370 so that the two eccentric
sleeves 360, 370 when combined cancel each other. Thus, the
stabilizer body 380 is oriented concentric to the rotational axis C
of the drill collar 310.
[0074] The inner sleeve 360 can move (rotate) relative to the drill
collar 310, and the outer sleeve 370 can move (rotate) relative to
the inner sleeve 360. The stabilizer body 380 can be part of or
connected to the outer sleeve 370 so that they move together, or
the stabilizer body 380 can move (rotate) relative to the outer
sleeve 370. Friction and torque may allow the various components to
move (rotate) relative to one another, and various features, such
as bearings, bushings, etc. found on rotary steerable system can
allow for the relative rotation.
[0075] Having an understanding of the elements of the stabilizer
component 340, its use in directional drilling will now be
discussed. Turning to FIGS. 7A-7B, the disclosed drilling assembly
300 is illustrated in a side view and an end view oriented for
concentric drilling. In this condition, the stabilizer component
340 is oriented with the two sleeves 360, 370 concentrically
arranged on the drill collar 310 so that the drill bit 320 rotate
with the rotational axis C of the assembly 300. Rotation of the
drill collar 310 and bit 320 is illustrated in direction
R.sub.A.
[0076] The actuator 350 is retracted so that its distal stop 356 on
the slide bar 352 engages the concentric stop 376 on the outer
sleeve 370. Thus, the outer sleeve 370 along with the stabilizer
body 380 is coupled for rotation with the actuator 350. Meanwhile,
the inner sleeve 360 with the slide bar 352 passing there through
is also coupled for rotation with the actuator 350. Because the
stabilizer component 340 can move (rotate) relative to the drill
collar 310, the component 340 may remain rotationally stationary in
the advancing borehole. Alternatively, depending on the torque
applied to the actuator 350 by the actuator assembly 330, the
component 340 may be allowed to rotate relative to the drill collar
310. In any event, relative movement either positive or stationary
for the component 340 is depicted as opposite rotation R.sub.B for
illustrative purposes. In other words, if the component 340 is to
be non-rotating in the borehole during concentric drilling, it
remains stationary while the drill collar 310 rotates.
[0077] As expected, the concentric drilling arrangement in FIGS.
7A-7B allow the drilling assembly 300 to advance a borehole
following along the central rotational axis C of the assembly 300.
The positive rotation R.sub.A can be imparted to the drill collar
310 and the drill bit 320 via drillstring rotation. Moreover, if
applicable for the implementation, the positive rotation R.sub.A
can be imparted to the drill collar 310 and/or the drill bit 320
via a mud motor (not shown).
[0078] When it is desired to use the stabilizer component 340 for
directional drilling purposes, the actuator 350 is activated by
operation of the actuator assembly 330. As shown in FIG. 8, the
linear actuator (332) of the actuator assembly 330 moves the
actuator 350 along the drill collar 310 as depicted in direction
S.sub.A. The distal stop 356 on the slide bar 352 comes free of the
concentric stop 376 on the outer sleeve 370. Accordingly, the inner
sleeve 360 is still configured to move (rotate) with the actuator
350, but the outer sleeve 370 is free to move (rotate) relative to
the inner sleeve 360. Torque applied by the clutch (334) of the
actuator assembly 330 allows the actuator 350 and the inner sleeve
360 to rotate in direction R.sub.C with the assembly's rotation
R.sub.A (i.e., the clutch (334) allows part of the collar's
rotation R.sub.A to be imparted to the actuator 350 and inner
sleeve 360). Meanwhile, the outer sleeve 370 and the stabilizer
body 380 can remain "non-rotating" by maintaining its relative
counter rotational direction R.sub.B.
[0079] Eventually, the proximal stop 354 on the actuator 350
rotates around to engage the eccentric stop 374 on the outer sleeve
370. FIG. 9A illustrate a side view of the disclosed drilling
assembly 300 rotated about 180-degrees from the other depictions so
the engagement of the proximal stop 354 with the eccentric stop 374
can be viewed. This eccentric activation orients the component 340
eccentric to the rotation axis C of the drilling assembly 300 so
that the drill bit 320 as shown in FIG. 9B is offset in a
displacement direction D.
[0080] To directionally drill, the offset direction D can be
oriented in the borehole so that the drill bit 320 advances toward
a desired trajectory. Using the inclination, azimuth, toolface, and
other information, the actuator assembly 330 can be controlled to
orient the offset direction D as needed. As shown in FIGS. 10A-10B,
the clutch (334) of the actuator assembly 330 can apply torque to
the actuator 350 to orient the offset direction D relative to the
toolface T.sub.F. Because the actuator 350 is engaged with the
eccentric stop 374, torque applied in rotational direction R.sub.D
can orient the offset direction to the desired toolface T.sub.F,
essentially by dragging the stabilizer component 340 around in the
borehole. Drilling can then continue with the offset direction D
oriented as desired. Changes to the trajectory can be made with the
actuator 350 operated by the actuator assembly 330 adjusting the
toolface T.sub.F of the offset direction D.
[0081] When a straight trajectory is again desired, the operational
steps for activating the offset direction D can be reversed. For
example, FIG. 11 illustrates a side view of the disclosed drilling
assembly 300 during an initial stage of deactivation. The linear
actuator (332) of the actuator assembly 330 retracts the actuator
350 so that its proximal stop 354 disengages from the eccentric
stop 374 on the outer sleeve 370. Eventually, through a reverse
operation of the activation steps, relative movement of the inner
and outer sleeves 360, 370 can then orient the concentric stop 376
to engage the distal stop 356 of the actuator 350 so that the
component 340 is arranged concentrically on the drill collar
310.
[0082] From this point, the activation and deactivation processes
can be repeated as necessary to drill the borehole along a
trajectory. Overall, operation of the eccentric stabilizer
component 340 of FIGS. 5-11 can follow and incorporate one or more
aspects of the operation characterized above with respect to the
previous embodiment of FIGS. 1-4B. For the sake of brevity, such
detail are not discussed again, but those detail would be
appreciated with the benefit of the present disclosure.
[0083] The disclosed eccentric stabilizer components 200 and 340
can be used with any other directional drilling tool used on the
drilling assembly 200 and 300. For example, the components 200 and
340 can be used with each other and/or with a directional drilling
tool, such as a mud motor with a bent sub, a rotary steerable
system, a point-the-bit system, a push-the-bit system, a targeted
bit speed (TBS) tool, etc.
[0084] The foregoing description of preferred and other embodiments
is not intended to limit or restrict the scope or applicability of
the inventive concepts conceived of by the Applicants. It will be
appreciated with the benefit of the present disclosure that
features described above in accordance with any embodiment or
aspect of the disclosed subject matter can be utilized, either
alone or in combination, with any other described feature, in any
other embodiment or aspect of the disclosed subject matter.
[0085] In exchange for disclosing the inventive concepts contained
herein, the Applicants desire all patent rights afforded by the
appended claims. Therefore, it is intended that the appended claims
include all modifications and alterations to the full extent that
they come within the scope of the following claims or the
equivalents thereof.
* * * * *